This application relates to a mold for forming a part having a portion extending away from the body of the part. More particularly, the present invention discloses a mold for forming such a portion wherein the part is automatically forced off the mold.
Plastic parts molded by conventional molds may have a portion utilized as a plug for attaching the part to a body by forcing the plug into an aperture in the body. As an example, the part could be a trim piece attached to a vehicle body. The plug has a first cross-section at a first distance from the body of the part and a second cross-section at a second distance from the body of the part wherein the second cross-section is thinner than the first cross-section and closer to the body of the part. In a sense, these plugs could be said to be dove-tailed in a plane moving away from the body of the part. It is sometimes difficult to define a cavity for forming such a portion of a molded part, since the cavity must allow the portion to be released from the mold when molded, while at the same time must define the dove-tailed shape while molding the portion.
There are known molds which define a dove-tailed cavity by having a pair of mold pins pivot relative to the cavity when actuated by an actuator. In these molds ejector pins are forced upwardly once the part has been formed to force the part away from a mold bottom. As the ejector pins are forced upwardly they also cause the mold pins to pivot outwardly to release the dove-tailed portion of the part. These prior art arrangements have proved somewhat unsatisfactory since the ejector stroke is also used to release and pivot the mold pins. In practice, the part often sticks to the mold pins and does not move off the mold bottom. Thus, an operator must monitor these molds and remove parts which do not move off the mold bottom.
It is an object of the present invention to disclose a mold that is capable of forming a dove-tailed cross-section wherein the part is released and then forced off of the mold such that the mold may be operated automatically, without supervision.
It is further an object of the present invention to disclose such an arrangement which is relatively sturdy, maintenance free, and requires few moving parts.